The Federal Register explains the embossings on 1M glass carboys:
http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/Federal%20Register%20Historical%20Files/44fr__1979/44fr-14194.pdf
§178.17~6 Markings.
(c) Except for Specification 1D glass carboys marked in accordance with the following markings must be embossed on the bottom of each carboy:
(1) DOT-1M;
(2) NRC;
(3) Year of manufacture; and
(4) Registration number (M****) of the manufacturer.
NRC stands for non-reusable container. The manufacturer number will not tell you the contents - just who physically made the carboy. I bought a 7.5 gallon M3008 at a garage sale for $3 and just cleaned/rinsed it in several stages before using the first time: B-Brite soak/scrub/rinse/rinse, bleach solution soak/rinse/rinse/rinse/rinse, idophor.
http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/Files/Federal%20Register%20Historical%20Files/44fr__1979/44fr-14194.pdf
§178.17~6 Markings.
(c) Except for Specification 1D glass carboys marked in accordance with the following markings must be embossed on the bottom of each carboy:
(1) DOT-1M;
(2) NRC;
(3) Year of manufacture; and
(4) Registration number (M****) of the manufacturer.
NRC stands for non-reusable container. The manufacturer number will not tell you the contents - just who physically made the carboy. I bought a 7.5 gallon M3008 at a garage sale for $3 and just cleaned/rinsed it in several stages before using the first time: B-Brite soak/scrub/rinse/rinse, bleach solution soak/rinse/rinse/rinse/rinse, idophor.
